Blender mesh missing loop
Edge Loops are not missing, it is expected behavior, it's an optimization done by Blender for faster viewport drawing.

If an edge angle is not sharp enough to be considered an actual corner it is not drawn in object mode unless you tick the option Draw All Edges under the Properties Window > Object > Display

If you have a Subdivision Surface modifier on your object, the Optimal Display option may also cause some edges to appear to be missing.